JP2629799B2 - Red-eye prevention control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a red-eye prevention control device for a camera that prevents a red-eye phenomenon during flash photography.

B. Prior Art The red-eye phenomenon is a phenomenon in which human eyes shine red or gold in color photography using an electronic flash device. This phenomenon occurs when the flash of the light emitting portion of the electronic flash device that has passed through the pupil of the eye is reflected by the retina, and the reflected light is reflected on the film. There are many capillaries in the retina of the eye, and the hemoglobin in the blood is red, so the reflected light appears reddish.

It has been empirically found that the red-eye phenomenon appears remarkably in a photograph under the following conditions.

1) When the imaging environment is dark The size of the pupil of the human eye changes depending on the surrounding brightness. When the environment is dark, the diameter of the pupil expands to about 7 to 8 mm. At this time, since the amount of incident light and the amount of reflected light to the eye are increased, the red-eye phenomenon is naturally prominent.

2) When the distance between the light-emitting part of the electronic flash device and the optical axis of the photographing lens is short. The retina of the eye has a considerably high reflectance and also has high directivity of reflection. Therefore, when the light emitting portion of the electronic flash device and the optical axis of the photographing lens are close to each other, and there are three elements (light emitting portion, photographing lens, and eyes) in a positional relationship in which regular reflection light from the retina easily enters the photographing lens as it is, the red eye Emits strong light. In other words, when the pupil of the person who is the subject looks at the angle between the photographic lens and the light emitting portion of the flash light source at a certain small angle or less, red eyes always occur. Empirically, this angle is about 2 to 2.5 degrees. Therefore, the occurrence of red eyes can be prevented by moving the light-emitting portion of the electronic flash device away from the optical axis of the taking lens. However, there is a limit due to the distance from the camera to the subject (hereinafter, referred to as the subject distance). It is difficult to avoid red eyes.

Therefore, techniques for preventing the red-eye effect have been conventionally known. For example, in the July 1952 issue of "psa JOURNAL"
A method is disclosed in which eyes are adapted to a bright environment before photographing, and a pupil is reduced to 3 mm or less and a flash is applied to prevent red eyes. Also, Japanese Patent Publication No. 58-48088 discloses that a pre-irradiation lamp is used for pre-irradiation by a pre-irradiation lamp just before photographing for a time necessary for closing the pupil. A technique for taking a picture by emitting light from a part is disclosed. In addition,
Japanese Patent Application Laid-Open No. 58-9130 discloses a method in which two flash discharge tubes are provided, one of the discharge tubes is pre-emitted to close the pupil, and then the second discharge tube is main-emitted to perform actual photographing. It has been disclosed.

C. Problems to be Solved by the Invention By the way, for example, photometry is performed in the central area and a plurality of peripheral areas of the object scene, and when the luminance of the central area is lower than the luminance of the peripheral area by a predetermined value or more, it is considered to be backlight. There is known a camera capable of so-called daytime synchronization, in which an electronic flash device emits light regardless of the brightness of a subject at the time of photographing to obtain an appropriate exposure, regardless of the brightness of a subject.

However, when this kind of daytime synchro function is incorporated in the above-described conventional camera that can prevent red eyes, unnecessary pre-irradiation is performed even in flash photography in a backlight against high brightness of a subject and no red eyes. In addition, the battery is wasted, and the opportunity of the pre-irradiation occurs frequently, giving an uncomfortable feeling to the subject. In addition, when the pre-irradiation is performed, the shutter release accompanied by the main light emission is delayed by the time required for reducing the pupil (about 0.75 seconds). May miss a photo opportunity.

An object of the present invention is to prevent red-eye prevention pre-irradiation at the time of flash photographing at the time of backlighting, prevent the battery from being wasted, do not cause discomfort to the subject, and miss a shutter chance due to unnecessary pre-irradiation. It is an object of the present invention to provide a red-eye prevention control device that prevents such a situation.

D. Means for Solving the Problems To be described with reference to FIG. 1 which is a diagram corresponding to the claims, the present invention provides a main flash device 101 for irradiating irradiation light for subject illumination.
And a red-eye prevention light-emitting device 102 for irradiating irradiation light for reducing the human pupil, and applied to a red-eye prevention control device that causes the red-eye prevention light-emitting device 102 to emit light prior to emission of the main flash device 101. Is done. The above-described problem is caused by a luminance information output unit 103 that outputs luminance information relating to the luminance of the subject, a determination unit 104 that determines whether the subject is backlit based on the luminance information, and a first predetermined luminance information. If it is higher than the predetermined value, the main flash device
When the luminance information is lower than the first predetermined value, the flash control means 105 activates the main flash device 101 regardless of the presence or absence of the backlight determination, and the luminance information is lower than the first predetermined value. When the brightness is higher than the second predetermined value, the operation of the red-eye prevention light emitting device 102 is prohibited regardless of the presence or absence of the backlight determination. When the luminance information is equal to or less than the second predetermined value, the red-eye prevention light emitting device 102 is disabled. The problem is solved by providing the red-eye control means 106 which allows the operation.

E. Operation When the luminance information is higher than the first predetermined value, the main flash is emitted when it is determined that the subject is backlit, but the pre-irradiation for preventing red-eye is prohibited regardless of the presence or absence of the backlit. When the luminance information is equal to or less than the first predetermined value and equal to or more than the second predetermined value, the main flash is emitted regardless of the presence or absence of backlight, but the pre-irradiation is prohibited. When the luminance information is equal to or less than the second predetermined value,
Both main flash emission and pre-reflection are performed.

F. Embodiment An embodiment of the present invention will be described with reference to FIGS.

2, a lens drive circuit 2, a focus detection circuit 3, a photometry circuit 40, and a camera control circuit 5 are connected to a CPU 1 via a signal transmission line BL1. The focus detection circuit 3 has a pair of light receiving elements made of, for example, a CCD, and forms a pair of subject images on these light receiving elements via a photographing lens RE and a pair of lenses (not shown). The CPU 1 outputs to the CPU 1 a focus detection signal indicating the amount of deviation between the image plane of the subject and the planned image plane and the direction based on the electric signal from the CPU.

The photometric circuit 40 includes five light receiving elements 41a to 41e, a head amplifier 42, an arithmetic circuit 43, and a memory path 44. The photometric circuit divides an object field into a central area and four peripheral areas, and performs photometry for each area.

The light receiving elements 41a to 41e respectively receive light from the central region and the four peripheral regions, convert the light into a photocurrent, and output the photocurrent to the head amplifier 42. The head amplifier 42 converts the input photocurrent into a logarithmically compressed voltage and outputs it to the arithmetic circuit 43. The arithmetic circuit 43 amplifies the input voltage to calculate the photometric data. These five photometric data are stored in the memory circuit 44, and are sequentially output to the CPU 1 from here.

An exposure control device 6 such as an aperture and a shutter and a display device 7 such as a liquid crystal display are connected to the camera control circuit 5. The camera control device 5 displays information on photographing such as an exposure value and a shutter speed on the display device 7 according to a command from the CPU 1 and drives the exposure control device 6 to perform photographing.

A motor 9 for driving the focusing lens 8 is connected to the lens driving circuit 2. The motor 9 is driven and controlled by a lens driving signal from the CPU 1 to drive the focusing lens 8 to perform focusing. Here, the lens drive signal is a signal formed by the CPU 1 based on the focus detection signal described above.

The CPU 1 includes an external electronic flash device 10 and a red-eye prevention light emitting device integrally formed with the electronic flash device 10.
11 is connected. The electronic flash device 10 controls a xenon tube Xe1 as a light emitting element, a main capacitor 10a for storing a charge for emitting the xenon tube Xe1, a charging circuit 10 for charging the main capacitor 10a, and the start and end of light emission of the xenon tube Xe1. Light emitting circuit 10c. Charging circuit 1
0b indicates that the charging of the main capacitor 10a is completed and the xenon tube X
When light emission of e1 becomes possible, a charge completion signal is output to CPU1. When the charge completion signal is input, the CPU 1 outputs a light emission start signal to the light emitting circuit 10c in response to turning on of a full-press switch SW2 described later. In response to this, the light emitting circuit 10b supplies the charged charge of the main capacitor 10a to the xenon tube Xe1 to start the xenon tube Xe1 to emit light. In addition, C
When the light emission stop signal is supplied from PU1 to the light emitting circuit 10c, the charge supplied to the xenon tube Xe1 is cut off and the xenon tube Xe1 is cut off.
To stop emitting light. The light emission amount of the xenon tube Xe1 is measured by the light control circuit 12, and is input to the CPU 1 as light control photometric data.

The red-eye prevention light emitting device 11 is a xenon tube Xe2 that irradiates light that reduces the pupil of the human eye, and a capacitor 11a.
It has a charging circuit 11b and a light emitting circuit 11c for controlling the start of light emission. When an operation signal is input from the CPU 1 to the light emitting circuit 10c, the xenon tube Xe2 emits light to perform so-called pre-irradiation.

Further, the CPU 1 is connected to a release switch SW interlocked with the operation of a release button (not shown). The release switch SW includes switches SW1 and SW2. The switch SW1 is turned on when the release button is half-pressed, and the switch SW2 is turned on when the release button is fully pressed. When the switch SW1 is turned on, the CPU 1 activates the focus detection circuit 3 and the photometry circuit 4 described above, calculates the distance D to the subject based on the focus detection signal input from the focus detection circuit 3, and switches the focusing lens 8 on. Calculate the lens drive amount for guiding to the joint position. Next, a lens drive signal is output to the lens drive circuit 2 to drive the focusing lens 8 to the converging position based on the lens drive amount. Also switch SW1
Is turned on, the CPU 1 switches from the memory circuit 44 of the photometric circuit 40 to the
One read the photometric data, calculates the subject luminance B ₁ .about.B ₅ of each region of the object scene on the basis of these data, the subject luminance B of exposure values for calculating these, for example, the average (luminance information) . Further also calculates the average value of the peripheral luminance B ₂ .about.B ₅ subjected to backlight determination. Thereafter, when the switch SW2 is turned on, the exposure control device 6 is driven via the camera control circuit 5 to perform photographing.

Further, the CPU 1 determines whether or not the electronic flash device 10 needs to emit light based on the level of the subject brightness B. When the subject brightness B is lower than a predetermined reference brightness value B ₀ , the electronic flash 10
When it is determined that light emission is necessary, the red-eye prevention mode is set to allow the operation of the red-eye prevention light emitting device 11, and the switch SW2 is set.
Activate the red-eye prevention light emitting device 11 in response to turning on the
After 0.75 seconds have elapsed, the exposure control device 6 is driven via the camera control circuit 5 and a light emission start signal is output to the light emitting circuit 10c.

Further CPU1, based on the five luminance information B ₁ .about.B ₅ determines whether a backlight as described later, when it is determined that the backlight is regardless electronic flash device of the level of the subject luminance B
Activate 10 and take a picture. However, the subject luminance B during the backlighting does not set a higher if red-eye prevention mode than the reference luminance value B ₀ of the above, prohibits the operation of red-eye preventing emission device 11.

In the configuration of the above embodiment, the electronic flash device 10 configures the main flash device 101, the photometric circuit 40 and the CPU 1 configure the luminance information output unit 103, and the CPU 1 configures the determination unit 104, the flash control unit 105, and the red-eye control unit 106, respectively. I do.

Next, the CP based on the flowcharts of FIGS.
The procedure of control by U1 will be described.

When the half-press switch SW1 is turned on, the program shown in FIGS. 3 and 4 is started. First, in step S1 in FIG. 3, the memory is reset to an initial value, and each circuit is reset. Thereby, the focus detection circuit 3 converts the detection result of the light receiving element into an electric signal and inputs the electric signal to the CPU 1. Also, the photometric data from the photometric circuit 40 for each area of the
Is input to Next, in step S2, the focus detection signal from the focus detection circuit 3 is read, and in step S3, the subject distance D is calculated, and the flow advances to step S4.

In step S4, the focusing lens 8 is determined based on the image shift amount and shift direction obtained by the above-described focus detection signal.
Calculates a lens drive amount for guiding the lens to the in-focus position, and outputs a lens drive signal to the lens drive circuit 2 in step S5.
The focusing lens 8 is driven to the in-focus position by the motor 9.

Then read the photometric data in each region of the object scene from the photometry circuit 40 at step S6, with each calculates a subject luminance B ₁ .about.B ₅ based on these photometric data in step S7, the subject luminance B ₁ ~ It calculates the subject luminance B by averaging the B _5. Next, in step S8 of FIG. 4, an exposure value (shutter speed and aperture value) is calculated from the field brightness B and the ISO sensitivity. These shutter speeds and aperture values are output to the camera control circuit 5 in step S9, and the camera control circuit 5 displays these values on the display device 7.
Display with.

Next, the process proceeds to step S10, where it is determined whether or not shooting is performed using the electronic flash device 10. This is determined based on whether the subject brightness B is high or low and whether the subject is backlit. That is, if the subject brightness B is lower than the predetermined reference brightness value B _0, it is determined that the electronic flash device 10 needs to be used, and if the subject brightness B is higher than the reference brightness value B ₀ , Further, whether or not the electronic flash device 10 is used is determined based on whether or not the light is backlit. For example, when the subject luminance B ₁ of the center region of the object scene is lower than a predetermined value than the average value of the subject luminance B ₂ .about.B ₅ near it is determined to be a backlit.

Then, the process is affirmed step S10 in the case of low or, alternatively backlit from the subject luminance B reference luminance value B _0, the process proceeds to step S11, not high and backlit subject luminance B is than the reference value B ₀ (frontlit In this case, step S10 is denied and the process proceeds to step S14. In step S14, the red-eye prevention mode is canceled, and the process returns to step S2. If the use of the electronic flash device 10 is prohibited by the electronic flash device use prohibition switch (not shown), step S10 is denied.

In step S11, it is determined whether or not the charging of the main capacitor 10a of the electronic flash device 10 has been completed, based on whether or not the charging completion signal has been output from the charging circuit 10b. The charging completion signal is output from the charging circuit 10b, and step S11 is performed.
If step S11 is affirmed, the process proceeds to step S12, and if step S11 in which the charge completion signal is not output is denied, the process proceeds to step S14.

In step S12, it determines whether the object brightness B is the reference brightness value B ₀ or less, if an affirmative the process proceeds to step S13. If step S12 is denied, the process proceeds to step S14 to cancel the red-eye prevention mode. Here, a negative result in step S12 indicates that the subject is backlit.

In step S13, the red-eye prevention mode is set, and thereafter, the process returns to step S2, and the processing in step S2 and subsequent steps is repeated.

When the full-press switch SW2 (FIG. 2) is turned on in this state, the interrupt routine shown in FIGS. 5 to 7 is started,
First, in step S21 in FIG. 5, it is determined whether the red-eye prevention mode is set. If a positive determination is made, step S2
Proceeding to 2, the light emission start signal is output to the red-eye prevention light emitting device 11 to cause the xenon tube Xe2 to emit flash light, so-called pre-irradiation is performed. As a result, the subject is a xenon tube Xe2
The pupil of the eye closes.

Next, in step S23, it is determined whether or not the time (for example, 0.75 seconds) when the pupil opening of the subject becomes minimum has elapsed after the light emission of the xenon tube Xe2. This is measured by operating a timer at the same time as a light emission start command to the xenon tube Xe2. If negative, step S2 until affirmative
It stays at 3 and waits for the above-mentioned delay time, and if a positive determination is made, the process proceeds to step S24. In step S24, the camera control circuit 5
Then, the main mirror is raised in step S25, and the shutter first curtain is driven in step S26. Thereafter, in step S27 of FIG.
0 Judge the use.

If step S27 is denied, the process proceeds to step S31, and it is determined whether a predetermined shutter opening time has elapsed. If step S31 is denied, it stays in step S31 until it is affirmed and waits for a predetermined shutter opening time, and if it is affirmed, it moves the shutter rear curtain in step S34, lowers the main mirror in step S35, and ends the processing. .

When step S27 is affirmed, the process proceeds to step S28, and it is determined whether or not the shutter is fully opened. If step S28 is denied, it stays in step S28 until it is affirmed and waits for the full opening of the shutter. To start. That is, main light emission is performed. Thereafter, the process proceeds to step S30, in which it is determined whether or not the shutter opening time has reached the synchronization tuning second. If the result is affirmative, the process proceeds to step S34.

If step S30 is denied, the process proceeds to step S32, and it is determined whether the light emission amount of the xenon tube Xe1 has reached a predetermined value. This is performed based on the photometric data measured by the dimming circuit 12 and input to the CPU 1. Step S32
If the result is negative, the process returns to step S30. If the result is positive, a light emission stop signal is output to the light emitting circuit 10c in step S33 to stop the light emission of the xenon tube Xe1. Thereafter, the processing is step S34
Proceed to. As a result, flash photography is performed when the pupil of the eye is minimized, thereby preventing the occurrence of red eyes.

According to the above procedure, as shown in the table below, when the calculated subject luminance B is equal to or less than the reference luminance value B ₀ , pre-irradiation by the red-eye preventing light emitting device 11 and shooting by the electronic flash device 10 Light emission follows. Also, the subject brightness B
Is higher than the reference luminance value B ₀ , only main light emission is performed at the time of backlight, and pre-irradiation is performed at the time of non-backlight (forward light).
Neither is performed nor the main light emission.

According to such an embodiment, the pre-irradiation for preventing red eye which is originally unnecessary is prohibited in the flash photographing at the time of the backlight, so that the battery is not undesirably consumed and the subject is uncomfortable. No more. In addition, it is possible to prevent a shutter chance from being missed due to unnecessary pre-irradiation.

In the above description, when the calculated subject luminance B is equal to or less than the reference luminance value B ₀ , that is, when an appropriate exposure is obtained using the electronic flash device 10, the red-eye prevention is always performed before the electronic flash device 10 emits light. Although the light emitting device 11 was made to emit light, for example, the main light emission is unnecessary as at dusk,
There may be shooting conditions under which red-eye does not occur. Therefore, under the following conditions, only the electronic flash device 10 may emit light without performing pre-irradiation even if it is not backlight.

Now, let B ₀₁ (<B ₀ ) be the limit luminance value of red-eye occurrence, and B ₀₁ <
If B, red eyes are not generated, and red eyes are generated when B ₀₁ ≧ B. This also in consideration of the limit brightness value B _01, as shown in the table below, when the B ₀₁ ≧ B to pre-irradiation and the emission, when the B ₀₁ ≦ B <B ₀ though backlight, a front light Unnecessary pre-irradiation can be further reduced by performing only main light emission, and further performing only main light emission when B> B ₀ and backlight, and not performing both light emission when B> B ₀ and forward light. .

In the above, although the subject luminance B ₁ of the object scene central region was made to determine the backlight is lower than a predetermined value than the average brightness value B ₂ .about.B ₅ 4 regions of interest such as a central region subject luminance B ₁ is may be judged backlit a low predetermined value or more than the subject luminance in a predetermined first area of the four areas around the. Alternatively, the backlight determination may be performed by another method.

Furthermore, although an example in which an external electronic flash device is mounted has been described, the present invention can be applied to a camera having a built-in electronic flash device.

Furthermore, if the periphery of the subject is bright, the pupil is reduced to some extent and the red eyes are not conspicuous, so whether or not to set the red-eye prevention mode may be determined according to the level of the luminance around the subject.

However, the subject brightness for exposure control is reflected light from the subject, and does not always match the degree of light stimulation received by the subject's pupil. Therefore, if light from all directions around the camera is received, luminance information equivalent to the degree of light stimulation received by the subject's pupil can be obtained. For example, a plurality of light receiving elements may be provided on each outer surface of the camera, or one light receiving element may be provided on each outer surface of the camera (a plurality of light receiving elements may be provided). It should just be arranged.

G. Effects of the Invention According to the present invention, when the luminance information is higher than the first predetermined value, the main flash is emitted when it is determined that the subject is backlit. Therefore, unnecessary pre-irradiation is not performed, unnecessary consumption of the power battery can be prevented, and the time between shutter releases can be shortened. When the luminance information is equal to or less than the first predetermined value and equal to or more than the second predetermined value, the main flash is emitted regardless of the presence or absence of backlight, but the pre-irradiation is prohibited. Without pre-irradiation, waste of the power supply battery can be prevented. Further, when the luminance information is equal to or less than the second predetermined value, both the main flash emission and the pre-irradiation are performed, so that the red-eye can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims. 2 to 7 show one embodiment of the present invention, FIG. 2 is a block diagram of a red-eye prevention control device according to the present invention, and FIGS. 3 to 7 are flowcharts showing processing procedures, respectively. 1: CPU 3: Focus detection device 10: Electronic flash device 11: Red eye prevention light emitting device 40: Photometric circuit 101: Main flash device 102: Red eye prevention light emitting device 103: Luminance information output means 104: Judgment means 105: Flash control Means 106: Control means

Continuing from the front page (72) Inventor Hachiro Kanai 1-6-3 Nishioi, Shinagawa-ku, Tokyo Nikon Oi Works Co., Ltd. (72) Toshio Sosa Inventor 1-6-3 Nishioi, Shinagawa-ku, Tokyo Japan Co., Ltd. Nikon Oi Works

Claims (1)

(57) [Claims] A main flash device for irradiating irradiation light for illuminating a subject; and a red-eye preventing light emitting device for irradiating irradiation light for reducing a pupil of a human, wherein the red-eye device emits light before the main flash device emits light. A red-eye prevention control device configured to cause the prevention light-emitting device to emit light; a luminance information output unit configured to output luminance information relating to luminance of the subject; a determination unit configured to determine whether backlight is generated based on the luminance information; When the information is higher than a predetermined first predetermined value, the main flash device is activated when the backlight is determined, and when the luminance information is equal to or less than the first predetermined value, the Flash control means for activating the main flash device regardless of the presence or absence of the backlight determination; and when the luminance information is higher than a second predetermined value lower than the first predetermined value, regardless of the presence or absence of the backlight determination. Red eyes Red-eye prevention control, comprising: a red-eye control unit that prohibits the operation of the light-emitting device for stopping, and permits the operation of the light-emitting device for red-eye prevention when the luminance information is equal to or less than the second predetermined value. apparatus.